Floyd Mayweather Jr. holds up a rare $500 from his money collection at his home in Las Vegas. / Ronda Churchill, For USA TODAY Sports

by Jon Saraceno, USA TODAY Sports

by Jon Saraceno, USA TODAY Sports

LAS VEGAS - Floyd Mayweather Jr., the man they call "Money,'' reaches into a closet in his opulent master bedroom and pulls out a cellophane-wrapped stack of cold hard cash.

Included in his batch of "Benjis'' and other denominations is a rare $500 bill, with William McKinley, the 25th president, on it and worth more than the face amount to collectors such as the unbeaten world welterweight champion. The U.S. printed the currency from 1862-1945 before the Nixon administration retired the bill in 1969, along with $1,000, $5,000 and $10,000 notes.

"It was a gift - one of my jewelers gave it to me,'' Mayweather tells USA TODAY Sports. "I like the old (U.S.) money. All of this is old money. You know, I've been all over the world so I've got money from everywhere.''

In other words, old money meets "Young Money."

Mayweather points out how the head size of Benjamin Franklin, who graces $100 bills, has expanded over the years.

The 36-year-old fighter, who will defend his crown against Robert Guerrero on Saturday at the MGM Grand Garden Arena, is an avid collector of many things. Among them: expensive watches, seductive cologne, boxing memorabilia (mostly his own) and his favorite mode of high-end Euro-styled transportation.

Mayweather's magnificent 22,000-foot home in a gated golf community overlooking the city contains multiple garages that boast glistening floors that are spotless for his collection of exotic pure-bred sports cars. Among them are two turbo-charged Ferrari beasts - a 458 Spider and a 59GT, plus a Lamborghini Aventador. All are white.

"I don't think I have a favorite,'' he says. "Everyone thinks it's my Rolls-Royce because I'm always in it on TV (documentaries). I'm blessed to be able to drive a Rolls-Royce every day. I think it's kinda cool.''